Louvre grille, 150x150 and 175x 175 and 210 x 210 mm and 240x240 – Galvanized Mounted with 4 screws. Can be used for all types of ventilation. Insect screen prevents insect intrusion. Dimensions (AxBxCxDxE): 148x148x11x130x130 mm Air passage: 23 cm². Dimensions (AxBxCxDxE): 175x175x12x155x155 mm Air passage: 40 cm². Dimensions (AxBxCxDxE): 215x215x13x195x195 mm Air passage: 123 cm². Dimensions (AxBxCxDxE): 240x240x12x220x220 mm Air passage: 123 cm